1506400 United States Covers. Pan Am Clipper. First flight, San Francisco to Guam.

 

Pan American Clipper.  First flight, round trip from San Francisco to Guam and returning to San Francisco, with both cachets, franked with (3) Scott 638 6c red orange.  Only a few were carried on both legs of the 6600 mile trip.  A wonderful opportunity for Clipper collectors.